I have downloaded and will read over the 130 pages.

But, from prior training and knowledge, the basic tennant of dealing with anything radioactive is: Time - Distance - Shielding.

Time - Radioactive material decays at an exponential rate. The further along you are on the decay, the less energy there is.
http://en.wikipedia.org/wiki/Exponential_decay

Distance - Radiation of all types (including light, thermal, and nuclear) follows the "Inverse-Square Law". For every foot away, the effective energy in the radiation decreases by some proportion of the original value.
http://en.wikipedia.org/wiki/Inverse-square_law

Shielding - Alpha, Beta, and Gamma particles are emitted from ionizing radiation are emitted from a nuclear device. This radiation poses a health hazard.

Alpha - Not a concern, unless direct contact (i.e. injested, on the skin, etc). I forgot the number, but I think a newspaper will protect you.
http://en.wikipedia.org/wiki/Alpha_particle

Beta - A little more penetrating. Apparently can be stopped with a few millimeters of aluminum.
http://en.wikipedia.org/wiki/Beta_particle

Gamma - This is the stuff that goes far distances. This is why you build 12 - 24" walls with lots of sand in them.
http://en.wikipedia.org/wiki/Gamma_particle

I am pretty sure that this is a "do the most good for the most people", and most people in an urban environment will have some shielding around them to limit/mitigate their exposure. The combination of time, distance and amount of shielding will determine their likelyhood of survival.

Evacuating people into the open will remove the shielding component, and could decrease the distance component. If you evacuate them early, you are on the "beginning" of the decay line, not further down, where the amount of energy is lower.

I took this FEMA Independent Study course a few years a go, and its a good review of basic High School nuclear physics, and gives some more useful information:

IS-3 - Radiological Emergency Management
http://training.fema.gov/EMIWeb/IS/is3.asp